This application relates generally to a turbine blade platform seal and damper assembly and specifically to a reversible blade damper within the assembly.
Conventional gas turbine engines include a turbine assembly that has a plurality of turbine blades attached about a circumference of a turbine rotor. Each of the turbine blades is spaced a distance apart from adjacent turbine blades to accommodate movement and expansion during operation. The blades typically include an attachment that attaches to the rotor, a platform that extends between pressure and suction sides, and an airfoil that extends radially outwardly from the platform. There is a gap between adjacent platforms.
A blade platform seal is utilized to span the gap, as relatively cool air for cooling the blade is radially inward of the platform, and the hot products of combustion are radially outward of the platform. The blade platform seal has typically also been associated with a damper which dissipates potential vibrations. The damper fits within pockets in the sides of the two adjacent blades.
The damper has four lugs extending in an axial direction away from a main damper body. Three of the lugs have extended generally perpendicular to the sides of the damper, and a forth lug has a circumferentially outwardly extending foot. The foot is received within a pocket in one side of one of the blades, and assures that the damper will not come out of its desired location between the two adjacent blades. In addition, a shoulder provides a radial reaction surface with a post on the blade.
In the past, the dampers may sometimes have been assembled relative to a seal 180° out of their proper orientation. When this has occurred, the circumferentially outwardly extending foot points toward the opposed blade, which has no need for the foot. The blade pocket which should receive the foot does not, and thus the damper has not always been adequately secured. In addition, the shoulder will be out of position relative to the post on the blade.
FIG. 1A shows a prior art damper 100. In the prior art damper 100, there is a seal slot 400 defined between two shoulders 102. The seal 70 (see FIGS. 1C/D) will be secured between the shoulders 102. A first lug 104 extends generally parallel to the sides 12 of the shoulders 102, as do lugs 110 and 112. These lugs all fit within pocket structure on the adjacent blades, as can be appreciated from the following disclosure. In addition, one lug 106 has a circumferentially outwardly extending foot 108.
There are shoulders 115 on an opposed end of a damper 100 from the foot 108. The shoulders 115 will contact a post on associated blades to provide a radial reaction surface. An axial reaction surface 114 will sit adjacent the posts.
FIG. 1B shows the bottom side of the damper 100. Axial Reaction Surface 114 also extends in a direction away from the seal, which is secured on the opposed side.
FIG. 1C shows an assembled damper 100 and seal 70 with the prior art damper. As shown, the lug 106 has its foot 108 extending in a direction such that the foot 108 will be properly received in a pocket in a blade. The shoulder 115 will be received above a post.
However, the prior art damper has sometimes been inadvertently mounted such that it is rotated by 180° from the position shown in FIG. 1C. This position is shown in FIG. 1D. Now, the circumferentially extending foot 108 points in the opposed direction, and will be spaced axially away from the desired position of FIG. 1C. With this arrangement, the straight lug 112 is received where the foot 108 is intended. The lug 112 will not secure the damper 100 within the blade pocket. In addition, the shoulder 115 is at an improper location, such that there will not be a radial reaction surface.
This is undesirable.